The Elder Scrolls: Equestria

Once upon a time in the magical Land of Equestria. There were two regal sisters who ruled together, and created harmony for all the land. To do this, the eldest, used her unicorn powers to raise the Sun at dawn. The younger brought out the Moon to begin the night. Thus, the two sisters maintained balance for their kingdom and their subjects. All the different types of ponies. But as time went on the younger sister became resentful. The ponies relished and played in the day her elder sister brought forth. But shunned and slept through her beautiful night. One faithful day, the younger unicorn refused to lower the moon to make way for the dawn. The elder sister tried to reason with her but the bitterness in the young ones heart transformed her into a wicked mare of darkness. Nightmare Moon. She vowed that she would shroud the land in eternal night. Reluctantly, the elder sister harnessed the most powerful magic known to ponydom. The Elements of Harmony. Using the magic of the Elements of Harmony she defeated her younger sister and banished her permanently in the moon. The elder sister took on responsibility for both Sun and Moon, and harmony has been maintained in Equestria for generations since...or that's how the story goes anyway. The truth, was far from it.

Yes Nightmare Moon was defeated by her sister. And the ponies of Equestria saw this as the defeat of a great evil. A victory for Equestria. Others however, didn't see Celestia's victory over Luna as a triumph. They saw it as an opportunity to strike. Celestia and Luna had ruled together for many, many years, and they had defeated mighty foes. The Spirit of Chaos, Discord. Sombra, the King of Shadows. And many other threats to ponykind. But Celestia always had Luna at her side. She hadn't defeated Discord alone, or Sombra all by herself. Without Luna Celestia was weakened. Equestria was weakened. And the Princess of the Sun knew it. It began slowly. A monster attack here. A usurper there. And Celestia showed no mercy. Slewing all who threatened her subjects. With Luna she had been strong enough to banish her foes, or merely imprison them. Without her, she couldn't risk them returning, and she couldn't protect the whole of Equestria alone anymore.

Thus the EUP Guard was formed. The Earth Ponies, Unicorns and Pegasi banded together under the banner of the Sun. and it seemed that Celestia's rule would be unchallenged. With a mighty army behind her who would dare threaten her subjects? Or the Kingdom they swore their lives to defend?

If history has taught us one thing its that there's always somepony who will challenge. Who will seek power that is not theirs.

And this time, it is no different.